Topic 13: Respiratory System - Pulmonary Ventilation Continued Flashcards
What is the stretch in lungs determined by? (2)
- compliance
- recoil
What is compliance? (2)
- effort needed to stretch lungs
- low = much effort
What is recoil?
- ability to return to resting size after stretch
What is both compliance and recoil a result of? (2)
- elastic CT and surfactant
What is lung collapse prevented by? (2)
- intrapleural pressure is ALWAYS below intrapulmonary
- presence of surfactant
Why does Pip always below Ppul prevent the lungs from collapsing? (3)
- pneumothorax = air into pleural cavity
- Patm = Ppul = Pip
- therefore lungs collapse and thoracic wall expands
What is surfactant? (2)
- lipoprotein/phospholipid mixture
- in water film coating alveoli to decrease surface tension
What is the purpose of surfactant? (2)
- allow easier stretch of lungs (increases compliance)
- prevents alveolar collapse
What is respiratory distress syndrome? (4)
- newborns < 7 months gestation
- inadequate surfactant so alveoli tend to collapse due to low compliance
- therefore effort is high
- leads to exhaustion and death
What is the formula for air flow and airway resistance?
F = air flow
deltaP = Patm - Ppul
R = resistance
What is resistance determined by?
diameter of bronchi/bronchioles
What is asthma, bronchitis, and emphysema caused by? (2)
- increased airway resistance
- more difficult to expire than inspire
______ (inspiratory/expiratory) mechanics open airways, while _____ close airways
1) inspiratory
2) expiratory
What does the SNS do to airway resistance?
- dilates bronchiolar smooth muscle (brochodilation)
What does PSNS do to airway resistance?
- contracts bronchiolar smooth muscle (bronchoconstriction)
